A huge variety of products, referred to generally as decals, and consisting essentially of a film-like material optionally bearing printed information and having an adhesive layer on one surface has been used to permanently or semipermanently identify objects or particular locations on objects. The medical arts have employed temporary decals, often referred to as temporary tattoos, as an improvement over making marks on a patient with a marking pen or adhesive tape for identifying the correct (or, perhaps, incorrect) site for a surgical or other invasive procedure or for the administration of a drug, high-energy radiation, etc. Such tattoos have also been employed to convey information about previous surgeries, pre-existing conditions, medications, etc. (e.g., U.S. Pat. No. 6,286,682, incorporated herein by reference in its entirety). Marks applied with marking pens can convey only limited information, often with poor legibility. In addition, such marks may be placed outside of the operative field, where surgical drapes etc. obscure the view of the mark. Adhesive tapes, even if they adhere well to skin, tend to interfere with the intended operative procedure because of their thickness and porosity, both of which tend to promote retention of bacteria. The film used in temporary tattoos, by contrast, is typically very thin. Its stability prior to use comes about because it is releasably secured at the surface opposite its adhesive surface to a water-permeable, relatively stiff, paper-like backing. The film's adhesive layer, in turn, is covered with a readily removable sheet of plastic material such as polycarbonate to protect the adhesive. The film serves as a substrate for inks applied by lithography (preferably, 4-color offset lithography) or “silk-screening,” or by ejecting ink onto the film from an inkjet printer head. The inks form images (letters, symbols, other patterns) on the film. Typically, the film, with backing sheet in place, is applied to the skin of a subject and then released from the backing by soaking the backing with water. Advantageously, the applied inks do not “bleed” substantially into one another or into adjoining layers before or after the tattoo is applied. Therefore, imprinted images remain sharply defined. Also, the inks do not diffuse from the film into living skin tissue. Moreover, the film and its applied inks and adhesive, although preferably moisture-resistant and mechanically resistant, are removable by innocuous means (e.g., soap and water).
Tattoos of this sort have provided a means of durably (but not permanently) labeling a body part with readable information that advises personnel administering care to the subject. The label conveys information about the medical procedure to be conducted in the proximity of the labeled site, and can carry additional information such as the name of the subject, the caregiver, etc. U.S. Pat. No. 6,579,252 to Lloyd et al., describes temporary tattoos whose printed indicia are intended to mark sites where a medical procedure is prohibited. U.S. Pat. No. 7,389,928 discloses a “medical system” of which a temporary tattoo is an element. The information on the tattoo is “bar-coded.” U.S. Pat. Nos. 6,579,252 and 7,389,928 are incorporated herein by reference in their entirety.
These and other examples in the prior art share the property of conveying relevant medical information by printing (or writing) the information on the tattoo's film element either before or after the film is applied to the patient's skin. The advantages of retaining a patient's “medical chart” directly on the patient are clear. However, inasmuch as invasive medical procedures are generally conducted in a sterile field that is typically provided by applying liquids that can dissolve or eradicate the film, information carried on the tattoo is also susceptible to eradication. Information lost during preparation of the field could include the medical procedure to be conducted, the site at which the procedure is to be conducted, and, most importantly, evidence that the accuracy of such information has been attested to or endorsed by the recipient of the treatment and/or by the responsible caregiver. What is needed is a means for retaining evidence of the attestation or endorsement in the operative field after the tattoo is eradicated, without compromising sterility or otherwise interfering with the procedure to be conducted, and without permanently tattooing the skin.